How does an integrated carrier calculate shipping charges?
If an order is eligible for an integrated shipping service, the integrated carrier checks the customer’s order information (i.e., shipment weight, shipment dimensions and origin/destination addresses) to assess an estimated shipping charge. Most often, the carrier uses only the Zip Code and not the entire address to compute the estimated charge. The actual shipping charge may slightly vary due to fuel surcharges and other fees when you create the actual delivery using the exact origin and destination addresses that the carrier requires to make the shipment. If this becomes a problem, you can consider adding a small handling fee to each integrated shipping method to help cover the spread between estimated shipping charges and actual shipping charges.
